The bait and switch aka the unit switcheroo is a classic pseudoscience technique beloved by antivaccine advocates. The general form used by antivaxxers is give a maximum dose of a scary sounding chemical and then say how much is in a vaccine. The amount in the vaccine exceeds the maximum dose recommended by the FDA or similar governing body. Panic ensues.
So what is happening here? Has the FDA just not noticed the amount of Scary Chemical X in vaccines? Are they deliberately allowing too much SCX in the vaccines to depopulate the world?Or is it just a case of antivaxxers having fun with units and hoping no one notices? Not surprisingly it is the last one.
Sometimes its a simple order of magnitude shift. A milligram here somehow becomes a microgram there. For example, say the daily maximum exposure to SCX is 0.2mg but a vaccine contains 3ug they will claim the vaccine has too much SCX in it. However they have switched units so what they should be saying is the maximum exposure is 200ug and the vaccine has 3ug. Consistency is the key.
The other, more common, trick is to state a total amount of something in a vaccine and then compare that to a rate. In this case the antivaxxer will say Vaccine A contains 100ug of SCX but the maximum dose of SCX in a day is 50ug/kg. What they are missing, intentionally or otherwise is the units have changed. It has gone from ug to ug/kg. You actually have to calculate the second amount on a person by person basis. Once you do even the most basic math you see that anyone over 2kg is going to be fine tolerating the full dose of SCX from Vaccine A.
So the next time someone tells you a vaccine has too much of a given chemical in it to be safe, check they are using the same units throughout. It’s an easy mistake to make but it’s not always a mistake. Sometimes it’s very deliberate.
Just as a note, I will come back to these in the future and add real examples. For now I just want to get the main ideas out.
Studoscience 